The long range goals of this research in atomic spectroscopy are to develop and improve quantitative methods for the analysis of both metal and nonmetal elements in biological samples requiring either microanalysis or trace analysis. The specific objectives of this project are to develop an analytical method which is sufficiently sensitive and accurate to support a study of the role of selenium in dilated cardiomyopathy, and to conduct the actual analyses of heart biopsy samples collected by Dr. Stern over approximately a 2-year period. This will involve the following steps: a. Develop a sensitive, accurate, and reproducible method for the analysis of selenium in 1-mg samples of biopsy tissue. The graphite furnace atomic absorption spectroscopic (GFAAS) method recently developed for the determination of selenium in tissue samples weighing 8 to 10 mg will be further miniaturized in order to analyze the ml-mg samples of cardiac biopsy tissue taken by hear catheterization so that the role of selenium in cardiomyopathy can be assessed. b. Verify the method by analyzing NBS standard samples (NBS 1577 and 1571), and other available samples such as beef heart. Conduct a homogeneity study on myocardium samples in order to determine if it is possible to perform selenium analyses on milligram size tissue samples and produce reliable results; the initial experiments will be conducted using beef he art. c. Analyze actual biopsy samples of cardiac tissue in a study designed to determine if serum selenium is an indicator for cardiac selenium. A study will be conducted which will involve the analysis cardiac biopsy tissue samples for selenium and the subsequent statistical evaluation of the results. Five to ten biopsy samples per month, which are taken for histological evaluation, will be analyzed for selenium after the histology studies are complete. The proposed study will be submitted by Dr. Stern to the appropriate committee at The University of Tennessee (Memphis) for approval. The required analyses will be done at Memphis State under the supervision of Dr. Williams. Previous work on quantitating selenium in human and animal tissues has been done on samples weighing a gram or more, and usually obtained from cadavers. Biopsy samples will necessarily be limited to approximately I mg. Reliable, reproducible data from such small samples will enable medical experts to assess the scope of selenium's role in dilated cardiomyopathy. This research will provide a sensitive, accurate technique for determining total selenium in cardiac biopsy tissue and/or blood serum. The method thus developed will then be used to analyze 5 to 10 heart biopsy tissue samples per month over a 2-year period thus producing a relatively large pool of data which will be used to help explain the role of selenium in heart transplants and dilated cardiomyopathy.